Why does your head hurt after a few drinks?

Red wine-induced headaches are often attributed to certain components in the drink, such as amines, sulfites or tannins, but to date no convincing evidence has been found to support these hypotheses, and no other explanation has been offered. However, the high concentration of flavonoids in red wine (ten times higher than in white wine) makes them prime suspects in causing headaches.

Headaches affect 16% of the world's population daily, and alcohol consumption is one of the main causes. Although excessive consumption of any type of alcohol can cause headaches, red wine is the biggest culprit: the headaches it causes occur more quickly than headaches caused by white wine, beer, or spirits.

There's another important difference: a red wine headache can be triggered by just one or two glasses, while other drinks only pose a problem after a large amount has been consumed.

When the liver metabolizes ethanol (the chemical name for alcohol), it turns into acetate through a two-step process. The first step is the reaction that turns it into a highly toxic substance called acetaldehyde.

The second step, catalyzed by the enzyme aldehyde dehydrogenase 2 (ALDH2), converts acetaldehyde to relatively harmless acetate.

However, about a third of East Asians lack the active ALDH2 enzyme. These people experience a buildup of acetaldehyde after drinking alcohol, causing facial flushing, nausea, and heart palpitations.

Although Caucasians generally have adequate ALDH2, drinking red wine appears to temporarily inhibit the activity of this vital enzyme. This means that after drinking red wine, but not other alcoholic beverages, Caucasians may experience a buildup of acetaldehyde similar to what happens in people who lack ALDH2.

Headache and wine

study⁽¹⁾ This study published on November 20, 2023 may have identified the culprit: a flavonoid called quercetin, which is one of 9,000 flavonoids included in many foods such as cabbage, onions, capers, cilantro, cranberries, green tea, apples and grapes.

When several wine flavonoids known to inhibit ALDH2 were tested, the most powerful was quercetin-3-glucuronide. This compound inhibited ALDH2 approximately three times more than all other compounds. This suggests that when we drink red wine, the liver converts quercetin into quercetin-3-glucuronide, which leads to a buildup of acetaldehyde.

It is important to note that quercetin alone does not cause headaches. Onions, for example, contain much more quercetin than wine, but few people complain of headaches after eating them: alcohol and quercetin work together to cause a buildup of toxic acetaldehyde.

The higher the quality of the wine, the more pronounced the headache

If the combination of quercetin and ethanol causes headaches, why can some people drink red wine without any effect, while others get headaches when they drink it? Several factors can explain this phenomenon.

Although the quercetin content in red wine is much higher than that of white wine, concentrations can vary greatly between red wines, depending on the type and origin. This is what we observed, among other things, in Spanish wines⁽²⁾.

Different wine-making processes, such as fermentation and aging, also affect the chemical composition that ends up in the bottle. The known factor is the degree of exposure of grapes to sunlight.

The vignobles that produce high-quality vins, the practices that tell the palissage, the efficiency and the defoliation allow for better receiving rays of sole lumière and more accumulative screens that in the conventional vignobles that produce the vins. Cheaper.

One study actually showed that total flavonoid content was four times higher in “high-quality” wines than in low-quality wines. This suggests that one way to avoid headaches might be, unexpectedly, to buy wine at a cheaper price.

Finally, the enzymes that metabolize quercetin can vary from person to person. Acetaldehyde may also cause headaches in people with only a genetic predisposition, as it occurs in a higher percentage of Asian people.

So, if you're one of the many people who are allergic to red wine, you can now explain why it gives you headaches while other alcohols don't!

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